Two‐dimensional (2D) materials are intensively attractive for fabricating high sensitive photodetectors in terms of atomically thin flexible and ultrafast charge transport feature. Due to their atomically thin body, designing high performance detector requires new physical mechanisms and device structures. In this review, we classify design strategies and device structures into four categories depending on their physical mechanisms (photovoltaic effect, photoconductive effect, photothermoelectric effect or photobolometric effect, and surface plasma‐ wave‐assisted effect), and summarize the device performances. Finally, future prospects and development direction for 2D material photodetectors are described. Those design strategies descriptions about photoelectronic detector provide a reference for high responsivity and fast response speed photodetector at broadband sensing in the future.

In the advancing field of optoelectronics, multifunctional devices that integrate both detection and processing capabilities are increasingly desirable. Here, a gate‐tunable dual‐mode optoelectronic device based on a MoTe ₂ /MoS ₂ van der Waals heterostructure, designed to operate as both a self‐powered photodetector and an optoelectronic synapse, is reported. The device leverages the photovoltaic effect in the MoTe ₂ /MoS ₂ PN junction for self‐powered photodetection and utilizes trapping states at the SiO ₂ /MoS ₂ interface to emulate synaptic behavior. Gate voltage modulation enables precise control of the device's band structure, facilitating seamless switching between these two operational modes. The photodetector mode demonstrates broadband detection and fast response speed, while the optoelectronic synapse mode exhibits robust long‐term memory characteristics, mimicking biological synaptic behavior. This dual functionality opens new possibilities for integrating neuromorphic computing into traditional optoelectronic systems, offering a potential pathway for developing advanced intelligent sensing and computing technologies.